1. Field of the Invention
The present invention relates to a cartridge for use in an image forming apparatus, and more particularly, relates to a cartridge for an image forming apparatus having an arrangement structure for shielding an electronic element from electromagnetic waves.
2. Related Art
Generally, a cartridge is detachably mounted to a main body of an image forming apparatus, such as a laser printer, a facsimile, a copy machine, a multi-functional product and so on, for forming images on printable media such as paper using an electro-photographic image forming process.
As shown in FIG. 1, the cartridge 10 includes a charging roller 11, a photosensitive drum 12, a developing roller 13, and a toner container 14. The photosensitive drum 12 and a transfer roller 21 within the main body of the image forming apparatus are engaged and rotated such that a toner image is formed on an individual sheet of printable media.
Since an amount of the toner which is stored in the toner container 14 of the cartridge 10 is limited, the cartridge 10 is provided with an electronic element 15 for measuring the amount of the toner in the toner container 14 and storing the same as data. The electronic element 15 includes a communication unit and a memory unit electrically connected to the communication to store information regarding the amount of toner contained in the toner container 14 and additional information such as the specification of the cartridge, an output condition and so on.
The electronic element 15 can also be arranged to communicate with the body of the image forming apparatus to perform information providing, data recoding and renewal and so on. Recently, the electronic element 15 having wireless communications capability has been packaged in a small sized cartridge to alert of any wire contact problem. However, when the electronic element having wireless communications capability, there has been a problem in that data stored in the electronic element 15 is often damaged due to noise generated according to an electromagnetic interference.
To resolve the above problem, there has been provided U.S. Pat. No. 6,438,327 which is entitled “PROCESS CARTRIDGE HAVING STORAGE DEVICE WHICH COMMUNICATES WITH IMAGE FORMING APPARATUS”, in which the electronic element 15 is positioned in a predetermined place of the cartridge 10, as shown in FIG. 1. According to this approach as disclosed by U.S. Pat. No. 6,438,327, contact lines P1, P2 and P3 between the photosensitive drum 12 and adjacent rollers, such as a charge roller 11, a developing roller 13 and a transfer roller 21, are indicated as main points in which electromagnetic waves are generated. In order to shield electromagnetic waves from the main points, as shown in FIG. 1, an electronic element 15 is attached to an inner wall of a waste toner container 16.
However, the conventional approach as disclosed by U.S. Pat. No. 6,438,327 considers only the rectilinearity of the electromagnetic waves. In other words, such a conventional approach does not consider other properties of the electromagnetic waves, including reflection, scattering and diffraction.
Meanwhile, a contact line P1 between the charge roller 11 and the photosensitive drum 12 to which the highest voltage is applied among the contact lines P1, P2 and P3 exerts great influence on the electronic element 15. Noise from the electromagnetic waves is mainly generated, when the charging voltage applied to the charge roller 11 is an alternating current (AC) voltage.
Therefore, notwithstanding the conventional approach as described by U.S. Pat. No. 6,438,327, there has been a problem in that data of the electronic element 15 included in the cartridge 10 is still damaged due to reflection, scattering and diffraction of electromagnetic waves generated from the contact line between the charge roller 11 and the photosensitive drum 12.
Accordingly, there is a need to efficiently shield an electronic element included in a cartridge from all characteristics of electromagnetic waves generated between a charge roller and a photosensitive drum.